Other Merge two XenForo froums.

I have two websites, my second website has died down so i would like to take those forums/members/posts and merge them into my main website. I am looking for somebody who can do this along with answer a few questions about the process. The main website is pjnorrath.com, the website that will be getting morged into it is pjpantheon.com.

1) How long/how much will it cost.
2) What happens when somebody is registered on both sites with the same info, does that person now have two accounts or do those accounts merge? (Is it possible to merge duplicate accounts)
3) Are there any potential downfalls or cons to doing something like this?

XenForo does not permit the same name or email address to be used for more than one user, so you will be required to confirm what to do in the case of any affected users. The options available are to merge them or rename and change the email address.